Comparison of fixed model and mixed model on analysis of block design data

• Main Authors: Chia-Kang Huang, 黃家康
• Other Authors: Ching Liu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/73438899214038842918

碩士 === 國立臺灣大學 === 農藝學研究所 === 102 === Blocking is commonly used in experiments as a local control method and to improve the efficiency. Block effects therefore should be regarded as ramdom rather than fixed. Unfortunately most textbooks on experimental designs treat block effects as fixed and the analysis formulae presented in the textbooks can only be used to handle the balanced data. Several commonly used block designs are analyzed as fixed model and mixed model separately and comparison of analysis results are made in this paper. We also compare the situations of balanced data and unbalanced data. Merits of general linear models by matrix formulae relative to traditional analysis by algebraic formulae are discussed, especially for mixed models and/or unbalanced data. Results indicate that many important statistics differ when cited data were analyzed assuming block effects as fixed and assuming block effects as random. For the purpose of making a logical statistical inference, block effects should be treated as random rather than fixed.